Growing hollyhocks can be one of the most stunning and rewarding acts of gardening you can do. There is nothing like hollyhock flowers at the height of their growth. Their bright blooms are perfect as a classic cottage garden staple. They attract hummingbirds and are a great addition to any garden.
Most people love hollyhocks for their ability to bring in hosts of pollinators, and their variety in color. They’re versatile in their ability to persist in varying amounts of sun and shade. Their blooms can last until early winter, and their perennial nature helps them return in spring.
Hollyhocks grow in a wide range of climates too. With their versatility in mind, maybe you’d like to grow your own garden of gorgeous flowers, including hollyhocks. What is needed for growing them, you ask? Let’s cover the basics so you can plant hollyhock seeds in spring.
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Quick Care Guide
|Common Name||Hollyhock, common hollyhock|
|Scientific Name||Alcea spp.|
|Family||Malvaceae, or the mallow family|
|Height & Spread||Up to 8 feet tall and 5 inches wide|
|Soil||Moist, rich, well-draining|
|Water||1 inch per week|
|Pests & Diseases||Rust, powdery mildew, spider mites, slugs, Japanese beetles|
All About Hollyhocks
Hollyhocks are manifold in their genus (Alcea), but the most common species of hollyhocks grown in North America are those of the Alcea rosea or common hollyhock. With over 80 species, gardeners are sure to find at least one hollyhock that works for them. Hollyhocks originated in China and made their way into the Middle East, and then to Europe via English soldiers during the Crusades. Crusaders used hollyhocks to make a salve that was applied to the hocks of horses injured in battle.
Hollyhocks grow on the sides of tall stalks that reach anywhere from 5 to 9 feet tall. Their base is covered in about 5 to 12 inches of heart-shaped leaves that become smaller as they grow up from the central stem. Their flowers form and bloom in mid to late summer after their second year of growth, but some bloom through fall, into the first part of winter. Hollyhock flowers sit atop the stem of the plant, reaching up to 3 inches wide. The flower is cup-shaped and comes in a wide range of colors.
After the hollyhock blooms and dies away at the end of the growing season, the petals fall and flat black seed heads form. As the pods dry, they pop open and spread their disc-like seeds on the soil surface below. Because hollyhocks readily self-seed and live for just a few years they’re considered a tender or short-lived perennial. As hollyhock seedlings emerge, their plant roots extend well below the surface. Like other members of the mallow family, hollyhocks have long taproots that go deep into the earth.
Hollyhock plants are commonly grown in cottage gardens to border the back of a garden bed. People also grow hollyhocks to attract hummingbirds, wasps, bees, butterflies, and beetles that assist in pollination. That’s why they’re a great flower to grow alongside a vegetable garden. Growing hollyhock flowers also means you’ll have a source for medicine.
Just as crusaders treated their horses with the flowers, growers might treat topical skin abrasions with them. The flower can also be made into a lovely medicinal tea that is reputed to treat the respiratory and digestive tracts. The flower stalks are a great addition to a summer flower bouquet too.
If you’re wondering when to plant hollyhock seeds, look no further! Since hollyhock plants are summer bloomers, start seeds one week before the last frost date. Plant hollyhocks in an area with ample sun, and fertile, well-drained soil. They will also grow easily in containers that are deep enough. When you grow hollyhocks, remember that you are growing a plant with a long taproot. Whiskey barrels are the suggested container of choice for them.
Rake the garden bed where you’d like to sow hollyhock seeds. Spread them thinly and evenly, trying not to overcrowd the bed with them. Then rake them in, and add soil if needed to ensure they’re ¼ inch covered. You can also plant hollyhocks from seed indoors and transplant them outdoors in your cottage garden. If you do this, make sure you have a grow light to give them adequate sunlight, and a good potting mix. After about 9 weeks of growth, they’ll be ready to plant outdoors.
Once you’ve planted seed or transplants it’s easy to grow hollyhocks. Even though this guide talks about their optimal conditions, hollyhocks can take a wide range of soil, temperature, and water content.
Sun and Temperature
Hollyhock prefers full sun, at about 6 hours per day. Partial shade is also adequate. Hard afternoon sun in a hot climate can be a little too harsh for flower production, so try to provide more shade in those areas while keeping with the six-hour minimum. The USDA growing zones for hollyhock range from zone 2 to 10. These short-lived perennials love temperatures between 60 and 90 degrees.
They don’t require cold hours but do best when nighttime soil temperatures stay between 60 and 65 degrees in their blooming season. Hollyhock plants are sensitive to frost damage and should be protected with a generous layer of mulch in winter or a spring freeze. Too much heat will stop blooming and prevent seed heads from forming. You can cover your hollyhocks in early spring and winter, but they’ll die away and come back on their own.
Water and Humidity
Water hollyhock plants in the morning at the base of the plant rather than above. Their leaves are susceptible to powdery mildew and rust, so irrigate at the base of the plant to avoid diseased leaves. There are some varieties of hollyhock that are susceptible plants and some that are rust-resistant, though. In warmer seasons water daily.
In more temperate seasons, water a few times a week. Because of their sensitive leaves, hollyhocks do best with soaker hoses or drip irrigation. Avoid watering when there has been ample rain. Although hollyhock isn’t drought tolerant, it can handle somewhat dry soil on occasion.
Most plants in the mallow family are tolerant of different types of garden soil. Optimal soil conditions for hollyhock include well-draining, fertile garden soil. A little bit of clay is just fine too. Poor quality soil is ok, but a small layer of compost on top of the planting area will help these plants bloom gorgeous flowers. Starter plants especially need rich soil or starter mix. The best pH range for hollyhocks is between 6.0 and 8.0.
Hollyhocks enjoy a fertilizer two times annually in temperate seasons. Well-balanced pellet or liquid soil-soak fertilizers are great. Find a fertilizer in your local garden center with an N-P-K of 10-10-10 or 15-15-15. Do not apply foliar fertilizer, as this promotes rust disease. Infected plants can spread disease to other susceptible plants, so avoid this if at all possible.
One of the coolest things about hollyhocks is they bloom multiple times in a season if they are treated properly. Deadheading hollyhocks is the key to multiple blooms. After the hollyhocks bloom, snip off the spent bloom with sharp and clean hand pruners. You can also pinch them off with your fingers. Then allow the seed head to fall and self-sow in the next growing season, or save seeds you collected this way for later.
When you deadhead hollyhocks there are a lot of options for seed saving and planting seeds (whole pods, separate seeds, and spreading seeds directly in the garden beds). When the parent plant turns brown in the fall, use your shears to cut it down to the ground. You can also leave a few stalks for overwintering bees and beetles to nest in.
The only mode of propagating hollyhocks is via their seeds from seed pods. You can collect the seeds throughout their season, and spread them in your garden one week before the last frost in spring. You could also plant the seeds in starter pots full of rich soil, placed in full sun.
Starting hollyhocks is pretty easy compared to other plants. After they’ve sprouted, place them in full sun outdoors 2 to 3 weeks after the last frost to harden them off for a few weeks. Then transplant them in the garden among other plants with flowers in a hole that is twice as wide as the root ball, and just slightly deeper. They should be established within a week or so.
When you grow hollyhocks, you’ll see they aren’t too fussy. They are host plants for pollinators, but they are also a host to fungal diseases and bugs. Let’s run those down!
When you grow hollyhocks, shield them from intense winds. Tall plants like hollyhock can snap in half in high winds. Though they don’t require stakes, it may be worth planting hollyhock – which can reach up to 9 feet tall – in an area backed by a garage or fence. The same goes for intense rain. 5 to 9 feet tall hollyhocks are sensitive to rain and hail.
When you grow hollyhocks in an area with poor drainage, they may be more susceptible to mildew. The same issue occurs when they grow too close to other plants. Hollyhock needs good air circulation to bloom and produce seed. Full sun is needed to prevent bacterial growth on the leaves in rainy seasons too.
Spider mites are insects that love to feed on the sap of the hollyhock plant and spin tight, dense webs in late stages. They cause stippling on leaves and eventually leaf drop. They typically enjoy dry hot weather, so look for them in warmer seasons. To treat them, first use a strong stream of water from a hose to knock them off the plant. Once the plant dries off, apply neem oil to all surfaces of the plant to prevent reinfestation.
Japanese beetles feed on the leaves of hollyhock. When you grow hollyhock, you’ll want to look for signs of them especially when hollyhock flowers are blooming. This is the peak of the beetle life cycle. Take some time to handpick beetles from the plant and flowers before they’ve had time to do damage. Applying beneficial nematodes (particularly Heterorhabditis bacteriophora) to the soil can reduce the population of beetle grubs overwintering, too.
Slugs are another pest that loves to feed on the plant matter of many hollyhocks. You’ll know they’ve been in your garden overnight when you see their slimy trails around the 5 feet tall spikes. Control them with diatomaceous earth sprinkled in the area where you grow hollyhock. An organic slug and snail bait is also incredibly effective.
When you grow hollyhocks you may have to contend with powdery mildew and hollyhock rust. Each is a fungal disease that starts from overly wet and warm conditions.
Powdery mildew can be controlled by avoiding wetting foliage during watering. You can also remove mildewed leaves as they are damaged. This type of mildew doesn’t often get to a point where an entire plant needs to be removed, but in close proximity to other plants, the mildew can spread. Neem oil or copper fungicide can reduce the risk of spreading
Particularly in hollyhock rust, fungal spores spread causing a relatively uniform dot formation on hollyhocks. You can avoid this altogether by planting rust-resistant seeds and plants. Some forms of rust can be treated by removing infected material and spraying the rest of the plant with either sulfur fungicide or copper fungicide.
Unfortunately, the most commonly sold hollyhocks (Alcea rosea) are not resistant to rust. So if you have to work with Alcea rosea in your garden, keep the area clear and clean of weeds. Cut down the plant at the end of the season. In fungal infestations, treat Alcea rosea with fungicide applied in spray form every 7 to 10 days. If that doesn’t work, remove the entire plant and dispose of it.
Frequently Asked Questions
Q: Do hollyhocks come back every year?
A: Most are tender perennials and return annually, but there are a few varieties that are annuals and live only one year.
Q: Where is the best place to plant hollyhocks?
A: Plant them in a full sun location with rich, well-draining soil.
Q: How long does it take for hollyhocks to grow?
A: They are biennial and don’t bloom until their second year. Seedlings are ready to transplant in 9 weeks. The entire lifecycle of a perennial variety is at least a few years, and potentially many more if you deadhead it!
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